<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        @media screen and (min-width:320px) {
            html {
                /* html中的文字大小 是屏幕尺寸除于我们划分的份数 一般为15份 */
                font-size: 21.3333px;
            }
        }

        @media screen and (min-width:750px) {
            html {
                font-size: 50px;
            }
        }

        div {
            height: 2rem;
            width: 2rem;
            background-color: pink;
        }
    </style>
</head>

<body>
    <div></div>
</body>

</html>